Sennhieser 650's

..using a dedicated balanced headphone amp.  The upgraded Cardas cable had a drooping shrink wrap so it went back to Cardas for a no charge fix.  In the interim, I plugged in the standard issue cables that came with it.  I don't know if the very obvious increase in fidelity was the Cardas, or that the phones are used balanced.....but there is a holy cow difference for the better with the Cardas....  Funny that Cardas isn't my cable of choice for the rest of the system.